.xaml
<ComboBox Grid.Row="0" Grid.Column="1" x:Name="cbx_srchResOrg" HorizontalAlignment="Stretch" Style="{DynamicResource ComboBoxStyle}"
ItemsSource="{Binding InfoCombo}" SelectedIndex="0" DisplayMemberPath="Dis_name" SelectedValuePath="Hide_id" SelectedItem="{Binding SelectInfo}"/>
Here is a part of my source code.
Why 'SelectedIndex=0' is not working?
I want to select [0] value to default at first time, but it just empty box at run time. There are no errors except it. How can I fix it?
As Hej said, you have binded the SelectedItem with a property in your view model which was null.
You can fix this by assigning the SelectedItem in your Viewmodel constructor
Public MyViewModel()
{
SelectInfo = InfoCombo[0];
}
Because you are already binding to SelectedItem. It binds two way by default, so if the property binded to it(SelectInfo) is null, it will also be set to null.
You can also use Mode=OneWayToSource in the SelectedItem binding with SelectedIndex="0".
In your case:
<ComboBox Grid.Row="0"
Grid.Column="1"
x:Name="cbx_srchResOrg"
HorizontalAlignment="Stretch"
Style="{DynamicResource ComboBoxStyle}"
ItemsSource="{Binding InfoCombo}"
SelectedIndex="0"
DisplayMemberPath="Dis_name"
SelectedValuePath="Hide_id"
SelectedItem="{Binding SelectInfo, Mode=OneWayToSource}"/>
Like others said, it binds two way by default, so if the property binded to it (SelectInfo) is null, it will also be set to null.
you have bind SelectedItem to SelectInfo, you should set value(in your viewmodel) to SelectInfo as default, for example
SelectInfo = InfoCombo[0] or something other whatevere you want to set as default value
Related
I am working on this problem for about a day now.
For some reason I am unable to TwoWay bind a value to a ComboBox if it is inside a ItemsControl. Outside works just fine.
I have an ObservableCollection of int? in my ViewModel:
private ObservableCollection<int?> _sorterExitsSettings = new ObservableCollection<int?>();
public ObservableCollection<int?> SorterExitsSettings
{
get { return _sorterExitsSettings; }
set
{
if (_sorterExitsSettings != value)
{
_sorterExitsSettings = value;
RaisePropertyChanged("SorterExitsSettings");
}
}
}
My XAML:
<ItemsControl ItemsSource="{Binding SorterExitsSettings}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<ComboBox ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=ItemsControl}, Path=DataContext.ScanRouter.Stores}"
SelectedValue="{Binding Path=., Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" DisplayMemberPath="name" SelectedValuePath="id" IsEditable="True" />
</DataTemplate>
</ItemsControl.ItemTemplate>
So the ComboBox is populated with a list of stores. It works fine so far.
The ObservableCollection SorterExitsSettings even has some values set which are shown in the displayed ComboBoxes. So setting the SelectedValue also works.
However when I change a selection, SorterExitsSettings wont change. While when I implement the ComboBoxes(100) without an ItemsControl it suddenly works fine.
<ComboBox ItemsSource="{Binding ScanRouter.Stores}" DisplayMemberPath="name" SelectedValuePath="id" IsEditable="True" SelectedValue="{Binding SorterExitsSettings[0], Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
Even better when I implement the ComboBoxes using the ItemsControl and also the example ComboBox shown above. When I change the single ComboBox's value it will change the value of the ComboBox inside the ItemsControl, but not the other way around.
Did somebody encounter this problem before?
My guess was that the ItemsControl doesn't like the fact that I am binding my selected value to an item in a list. However when I bind directly to a ViewModel property(Store) it also doesn't work.
I also tried using SelctedItem instead of SelectedValue and populate the ObservableCollection with Store objects instead of int?.
The problem is that you're binding your ComboBox's SelectedValue directly to the collection elements which are type int ?. This won't work, binding targets have to be properties. Try wrapping your int ? values in a class and expose the value as a property of that class with a getter and setter, i.e. something like this:
private ObservableCollection<Wrapper> _sorterExitsSettings = new ObservableCollection<Wrapper>();
... etc...
And:
public class Wrapper
{
public int? Value {get; set;}
}
And finally:
<ComboBox ... SelectedValue="{Binding Path=Value, Mode=TwoWay...
Post back here if you still have problems.
I have a ComboBox that is bound to an EnumerableRowCollection<T> :
ComboFamilyStatus.ItemsSource = EnumerableRowCollection<TaxDataSet.SourcesOfValuesRow> coll;
My xaml lookes like this:
<ComboBox Name="ComboFamilyStatus" DisplayMemberPath="Description"
Text="{Binding FamilyStatus, Converter={StaticResource FamilyStatusStringConverter}}">
I'm using the DisplayMemberPath to show the description of the row. The SourcesOfValuesRow has a value and a description and in the combo I want to see the description text. The Text is bound to the database where the FamilyStatus is saved as an int value this is why I added a converter.
My question is if the converter could convert from the int value to the string using the itemsource from the combobox? I don't see that the converter knows anything about the combo. In the meantime I wrote the converter to take again the EnumerableRowCollection<TaxDataSet.SourcesOfValuesRow> from the database and find there the matched description - this can't be the simplest way to do this!
Any suggestions??
In this case, you're better off using a DataTemplate, instead of a Converter.
You already have a data class. Just use a DataTemplate that inserts a Textblock bound to the int value, then apply your converter there.
<ComboBox>
<ComboBox.ItemTemplate>
<DataTemplate DataType="{x:Type local:TaxDataSet.SourcesOfValuesRow}">
<TextBlock Text="{Binding FamilyStatus, Converter={StaticResource FamilyStatusStringConverter}}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
<ComboBox>
Change your SourcesOfValuesRow FamilyStatusProperty to an enum. Deriving from int lets you cast it directly.
enum FamilyStatusValues : int
{
[Description("Married")]
Married,
[Description("Divorced")]
Divorced,
[Description("Living Together")]
LivingTogether
}
Then in your converter use this code
ConvertTo(object value, ...)
{
FieldInfo field = value.GetType().GetField(value.ToString());
object[] attribs = field.GetCustomAttributes(typeof(DescriptionAttribute), true));
if(attribs.Length > 0)
{
return ((DescriptionAttribute)attribs[0]).Description;
}
return string.Empty;
}
There is no need to use any converter. It worked for me using this:
<ComboBox Name="FamilyStatus" Grid.Row="7" Grid.Column="1" ItemsSource="{Binding Source={StaticResource comboProvider}}"
SelectedValuePath="Value" DisplayMemberPath="Description" SelectedValue="{Binding FamilyStatus}">
Where DisplayMemberPath is the string from the TaxDataSet.SourcesOfValuesRow and SelectedValuePath is the int value. The SelectedValue is the value from the contact table (instead of writing in the combo Text="{Binding FamilyStatus, Converter={StaticResource FamilyStatusStringConverter}}).
I have a ComboBox in my wpf application.
It's ItemsSource is binded to some table in my DataSet.
I need the text property to be binded to another's object property . I doesn't work because the ComboBox doesn't want to get two DataContexts. How can I solve this problem?
<StackPanel Width="Auto" Height="Auto" MinWidth="296" Orientation="Vertical" x:Name="MyStackPanel">
<ComboBox x:Name="MyComboBox" ItemsSource="{Binding}" Text={Binding Path=MyProperty} />
</StackPanel>
In the code behind :
MyComboBox.DataContext = MyDataSet.Tables[MyTable];
MyStackPanel.DataContext = MyObject;
I want the ComboBox to show items from one DataContext but to show the text from another DataContext. How can I do it?
Don't use DataContext. Set the Source property of your bindings in XAML or create the bindings in code and set the Source property there.
Why are you assigning something to the datacontext of the stackpanel? From the looks of it, its not used.
Your code should work if MyDataSet.Tables[MyTable] returns an enumeration and contains a property called MyProperty.
What do you mean when you say that the combobox "doesn't want to get two DataContexts"?
Look into the properties IsEditable and IsReadOnly of the combobox.
Something like
<ComboBox x:Name="MyComboBox" ItemsSource="{Binding}" Text={Binding ElementName=MyStackPanel Path=DataContext.MyProperty} />
I a have a View Players, the datacontext is set to a ObservableCollection Players from the ViewModel MainPlayerViewModel.
In the View I have a datagrid with columns TeamId, Name and Position.
I want to bind the TeamId column with a combobox to a list of available teams from the MainTeamViewModel which has a collection property Teams but of course I want the MainPlayerViewModel to be updated whenever I update the team for a player.
I hope you can follow me here..
This is my xaml:
<data:DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<ComboBox DataContext="{Binding MainTeam, Mode=OneWay, Source={StaticResource Locator}}"
Height="23" HorizontalAlignment="Left"
Name="cmbTeams" VerticalAlignment="Top" Width="100" ItemsSource="{Binding Teams,
Mode=TwoWay}" SelectedValue="{Binding Path=Model.teamid, Mode=TwoWay}"
DisplayMemberPath="Model.teamid"/>
</DataTemplate>
</data:DataGridTemplateColumn.CellEditingTemplate>
When I edit the cell it shows the list of available teams but the selectedvalue I pick from the list doesn't turn up in the TeamId column
How do I pull this off?
Kind regards,
Mike
UPDATE:
Despite the help I received I didn't get it to work binding one View to 2 different Viewmodels.
Guess the solution offered is long above my head..
I couldn't set the datacontext of the datagrid to MainTeam because it has an ItemsSource of players and a selecteditem bound twoway to selectedplayer.
Anyway I decided to keep it 1 View / 1 ViewModel and created a public property on my PlayerViewModel named teamsVM:
public MainTeamViewModel teamsVM
{
get
{
return ViewModelLocator.Container.Resolve<MainTeamViewModel>();
}
}
Now I can set the Itemsource to this new property and my player row get's updated when I change teams:
<DataTemplate>
<ComboBox
Height="23" HorizontalAlignment="Left"
Name="cmbTeams" VerticalAlignment="Top" Width="100"
ItemsSource="{Binding teamsVM.Teams,
Mode=TwoWay}" SelectedValue="{Binding Model.teamid, Mode=TwoWay}"
DisplayMemberPath="Model.teamid" SelectedValuePath="Model.teamid"/>
</DataTemplate>
Regards,
Mike
I find two things wrong with this code.
You are missing the SelectedValuePath for the ComboBox. Even though you bind all teams to it, the selected item's id is null because the SelectedValuePath is missing.
You also have a DataContext and an ItemsSource. Use only the ItemsSource for the teams you want to display, and the SelectedValue to be bound to the player's teamId, unless your view model has a "Teams" property and a "Player" property, in which case the DataContext may be used. (Id set the DataContext in code though...)
So yo will end up with something like this:
ItemsSource="{Binding Teams, Mode=TwoWay}" //Bind to all teams.
SelectedValue="{Binding Player, Path=TeamId, Mode=TwoWay}" //Bind to the teamId of the player.
DisplayMemberPath="TeamName" //that's the Name of each team.
SelectedValuePath="TeamId" //that's the Id of the team.
Two problems here:
First, as #bleepzer noted you did not specify the value/display paths in your combo box.
Second, you trying to access a property in the data context that is outside your grid (i.e. the main view model's data context) from within a data template. In silverlight 4 there is no relative source binding (something you would use in SL 5 or WPF), so you will have to use element binding to archive what you want.
Here is an example based on your code. It is not complete as it leaves out some of the DataGrid elements needed, but it shows the concept:
<data:DataGrid x:Name="myDataGrid"
DataContext="{Binding MainTeam, Mode=OneWay, Source={StaticResource Locator}}" >
<!-- additional stuff needed here -->
<data:DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<ComboBox Height="23" HorizontalAlignment="Left"
Name="cmbTeams" VerticalAlignment="Top" Width="100"
ItemsSource="{Binding ElementName=myDataGrid, Path=DataContext.Teams}"
SelectedValuePath="TeamId"
DisplayMemberPath="TeamName"
SelectedValue="{Binding Path=Model.teamid, Mode=TwoWay}"/>
</DataTemplate>
</data:DataGridTemplateColumn.CellEditingTemplate>
<!-- additional stuff needed here -->
<data:DataGrid>
And here is the description:
Add a name to your data grid.
Make sure the data grid has the right data context, either by setting it explicitly as in the sample, or inheriting it from the parent hierarchy.
Modify your ComboBox's ItemsSource property to point to the data grid using the element name you specified earlier. As you are now on the element and not on the data context you have to use DataContex.Teams to access the Teams property on the data context of your grid. The ItemsSource does not need two-way-binding as the view does not write anything back to your view model.
Specify the SelectedValuePath and DisplayMemberPath properties.
Finally, bind the SelectedValue property of the combo box to your rows model TeamId property using two-way-binding - needed now as the view should update the model's value. Important: the SelectedValue property of the combo box has to be bound after the ItemsSource to prevent some problems with the combo box.
I want to populate a TreeView with UserControls, but I only want the Name property to show up, not the entire UserControl. The following code gives me weird crashes as soon as I add something to myUCs:
C#:
var myUCs = new ObservableCollection<UserControl>();
MyTreeView.ItemsSource = myUCs;
XAML:
<controls:TreeView x:Name="MyTreeView">
<controls:TreeView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</controls:TreeView.ItemTemplate>
</controls:TreeView>
Does anyone know how to use a list of UserControls as an ItemSource for TreeViews?
I found one not so convenient workaround: instead of a List of UserControls, use a Dictionary, and change the XAML to:
<controls:TreeView x:Name="MyTreeView">
<controls:TreeView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Key.Name}"/>
</DataTemplate>
</controls:TreeView.ItemTemplate>
</controls:TreeView>
The same bug(?) exists in ListBox, a solution is provided here:
Use UIElements as ItemsSource of ListBox in Silverlight
That particular fix does not work for TreeView
You may have to create your own class that extends UserControl and override the ToString() method so that it returns the name property.